This invention relates to means for positioning the end of yarn on a cross-wound bobbin and more particularly for such means in a textile machine that has a plurality of winding heads and a traveling service mechanism that services the winding heads individually for a final treatment of the cross-wound bobbins after they have been released from their bobbin drive but are still held in the creel of the winding head between bobbin tube holding elements that are rotatably mounted in the creel, with a bobbin-rotating device that can move toward and away from the bobbin and with a yarn take-in deivce for searching for, taking and drawing off a yarn end that has been wound onto the surface of the cross-wound bobbin. The service mechanism can be, for example, a cross-wound bobbin changer, a piecer, a combination of both devices or any other mechanism that can travel on the machine.
It is desirable in many instances in the further processing of cross-wound bobbins to wind a yarn end onto an end of the bobbin tube as a yarn reserve or end reserve in order to be able to find the yarn end better in subsequent processing of the yarn.
Thus, German DE-OS No. 17 60 243 teaches that a strip can be pivoted upward about a pivot point located to the side of the bobbin directly in front of a yarn guide traveling back and forth in order to guide the yarn to one side of the bobbin. Such a device must be present on each bobbin, which results in a complicated and expensive mechanism.
The same publication discloses a friction roller driven in both directions of rotation and a suction tube connected to a suction blower with the roller and suction tube being movable onto a cross-wound bobbin mounted in a freely rotatable manner, with the suction opening of the suction tube extending over a part of the circumference and the entire length or a portion of the length of the bobbin.
This prior device takes up the bobbins removed from the winding head in order to process them and in doing so may catch the yarn in the path of the device such that it is difficult to locate. Moreover, such a device is very complicated due to the necessary feed and removal devices. Further, the possibility of using such a device is limited because it requires a considerable amount of space around and to the side of the bobbin which is not normally available in this type of machine for producing cross-wound bobbins.
DE-OS No. 25 06 930 teaches that the end reserve can be formed by removing the bobbin from the winding device and rotating it slowly counter to the direction of winding, pneumatically catching the yarn end and removing it with a suction gripper, with the mouth of the suction gripper pivoting to one end of the tube and delivering the yarn end to the tube. Since in this device the bobbin must be removed from the winding device, a complicated holding and drive device for the bobbin is necessary. Also, the gripper must execute complicated movements in order to grasp the yarn and deliver it to the tube, and the device can be used only in a limited manner because enough free space for the movements of the device is usually not present in machines that wind cross-wound bobbins.